Incidence rates have been shown to depend on the nature of the SCI. Verschueren et al. (2011) noted that 9.8% of non-traumatic SCI patients and 22.8% of traumatic SCI patients had DVTs. No significant difference has been noted in the incidence of DVT based on AIS scores (p=0.58; Sugimoto et al. 2009).

In an analysis by Cao et al. (2013) examining risk factors for mortality, the authors did not find that DVT was significantly associated with future mortality. The study was based on evidence from 22 studies and provides insight into the methodological issues noted by studies when reporting incidence rates. Current findings suggest that early recognition of DVT and successful treatment are necessary in reducing the likelihood of mortality.

The high risk of DVT in acute SCI patients is due to the simultaneous presence of three factors of Virchow’s triad: hypercoagulability, stasis, and intimal (inner vessel layer) injury (Aito et al. 2000). Venous thromboembolism usually begins with a calf DVT (Nicolaides et al. 1971; Philbrick et al. 1988; Cogo et al. 1998). Other contributing factors include partial or total limb paralysis and absence of spasticity which is a signifi­cant independent risk factor for DVT (Do et al. 2013). Venous thromboembolism affects blood flow, reduces the capacity of the vessels and increases the venous resistance. These as a result promote a cascade of metabolic derangements resulting in activation of the coagulation cascade and venous thrombosis (De Campos Guerra et al. 2014).